The present invention relates generally to nasogastric tubes used, for example, to aspirate fluids from the gastrointestinal tract, or as feeding tubes for administering medicines or nutrients to a patient.
The primary purpose of a nasogastric tube is to aspirate fluid and air and decompress the contents of the stomach without damaging the gastric mucosa. In this regard, indwelling nasogastric tubes are used for clinical applications designed to remove accumulated fluids or blood from the stomach or gastrointestinal tract due to intestinal obstruction and consequent to decreased gastrointestinal function following abdominal surgery, bleeding ulcers or disease.
Nasogastric tubes are frequently placed in patients undergoing laparoscopic and open abdominal surgery to keep the stomach empty. In addition patients with intestinal obstruction and paralytic ulcers (temporary paralysis of the stomach/intestinal tract) may require a nasogastric tube to prevent progressive distension of the stomach/intestional tract. Progressive distension of the stomach/intestinal tract can lead to vomiting, shock, and visceral injury. In a severely ill patient, vomit may be aspirated into the respiratory tract and cause asphyxia and pneumonia.
The physician typically introduces the nasogastric tube which is conventionally a double lumen flexible plastic tube through one nostril, through the oropharynx and through the esophagus into the stomach for aspirating fluids or the duodenum for feeding. The distal end of the tube in the stomach includes several openings suction ports or openings for permitting the passage of gastric fluids. The proximal end of the tube exits the nostril, is pulled to the side of the patient's head and may be taped to the skin and is normally connected through a collector vessel to a suction source. Thus, stomach fluids are drawn through the openings in the distal end, through the tube into the collector vessel.
The nasogastric tube contemplated by the present invention is a double lumen sump tube of the type discussed above used to decompress the stomach in a manner well known in the art. The large lumen is used for suction drainage and irrigation and is connected to a suction source providing either intermittent or continuous suction. The smaller lumen vents the suction drainage lumen to the atmosphere through a perforation or opening in the distal end of the tube. With a dual lumen sump tube, the constant flow of atmospheric air moderates the amount of suction and flow from the stomach never stops, provided the suction openings do not become clogged and the sump lumen obstructed and filled with gastric fluids.
During normal suctioning operation of the nasogastric tube, a small amount of atmospheric air is drawn through the sump lumen into the stomach and suction lumen at the distal end. If there is fluid in the sump lumen due to reflux (i.e. stomach fluids backing up into the sump lumen), the required constant flow of incoming air is not provided. Thus, a non-functioning tube may actually be detrimental to the patient. As mentioned earlier, if air/gastric fluids are not removed, progressive distension of the stomach/intestinal tract can result in vomiting and other complications like pulmonary aspiration and asphyxiation. Accordingly, proper operation of the double lumen nasogastric tube depends on the continuous availability of atmospheric air to the suction openings at the distal end through the cooperation between the suction lumen and the sump lumen at the distal end.
A common problem encountered in using nasogastric tubes is the clogging or occlusion of the openings in the distal end leading into the suction lumen. The clogging may be the result of stomach debris, covering the openings or occlusion could be the result of the openings laying against the stomach or gastric mucosa. In either event, the air/gastric fluids cannot be suctioned.
In the event stomach pressure becomes greater than atmospheric pressure, gastric reflux can occur, causing stomach fluids to escape through the sump lumen. Unfortunately gastric reflux is a common problem with nasogastric tubes. Stomach fluids backing up the sump lumen and spilling onto the bed sheets, patient's clothing and even onto the patient is bothersome, a nuisance, and potentially dangerous because of the possible exposures to infectious body fluids and blood and contaminated laundry by doctors, nurses, clinicians and hospital staff. In this regard, studies have shown that the digestive tract is the main cause of aerobic gram-negative bacteria, the most frequent cause of ICU infections. Of course contaminated blood of a patient may cause other serious problems.